CVE-2023-40577

Prometheus Alertmanager is vulnerable to cross-site scripting due to improper validation of user-supplied input by the /api/v1/alerts endpoint. This issue could allow a remote attacker to inject malicious script into a web page, which would be executed in a victim’s web browser within the hosting website once the page is viewed, allow the attacker to steal the victim’s cookie-based authentication credentials.

Mitigation

Users can setup a reverse proxy in front of the Alertmanager web server to forbid access to the /api/v1/alerts endpoint.